Method for hydroformylating cyclooctadiene using 2-(anthracen-9-yloxy)-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane

ABSTRACT

Method for hydroformylating cyclooctadiene using 2-(anthracen-9-yloxy)-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane.

The invention relates to a method for hydroformylating cyclooctadiene(COD) using2-(anthracen-9-yloxy)-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane.

Phosphorus-containing compounds, as ligands, play a crucial role in amultitude of reactions. Said compounds include phosphite ligands, i.e.,compounds comprising P—O bonds, used in hydrogenation, hydrocyanationand especially hydroformylation.

The reactions between olefin compounds, carbon monoxide and hydrogen inthe presence of a catalyst to give the aldehydes with one carbon atommore are known as hydroformylation or the oxo process. In thesereactions, compounds of the transition metals of group VIII of thePeriodic Table of the Elements are frequently employed as catalysts.Known ligands are, for example, compounds from the classes of thephosphines, phosphites and phosphorites, each with trivalent phosphorusPIII. A good overview of the status of hydroformylation of olefins isfound in R. Franke, D. Selent, A. Börner, “Applied Hydroformylation”,Chem. Rev., 2012, DOI:10.1021/cr3001803.

The object of the invention is to provide a method for hydroformylatingcyclooctadiene which affords good conversion of cyclooctadiene.

The object is achieved by a method according to claim 1.

Method for hydroformylating cyclooctadiene, comprising the method stepsof:

a) initially charging cyclooctadiene;

b) adding a complex comprising:

-   -   a metal atom selected from: Rh, Ru, Co, Ir, and    -   a ligand having the structure (1):

or

adding a precursor complex comprising a metal atom selected from: Rh,Ru, Co, Ir, and a compound having the structure (1):

c) feeding in H₂ and CO,

d) heating the reaction mixture, wherein the cyclooctadiene is convertedto an aldehyde.

Here, method steps a) to d) can be effected in any desired sequence.

In one variant of the method, the metal atom is Rh.

In one variant of the method, the precursor complex comprisescyclooctadiene.

In one variant of the method, the precursor complex is [(acac)Rh(COD)].

In this instance, “acac” is acetylacetonate anion and “COD” iscyclooctadiene.

In one variant of the method, the reaction mixture is heated to atemperature in the range of 50° C. to 70° C. in method step d).

The invention is elucidated in detail hereinafter by working examples.

Analysis

Chromatography

The preparative liquid chromatography separations via flashchromatography were conducted with a maximum pressure of 1.6 bar on 60 Msilica gel (0.040-0.063 mm) from Macherey-Nagel GmbH & Co, Duren. Theunpressurized separations were conducted on Geduran Si 60 silica gel(0.063-0.200 mm) from Merck KGaA, Darmstadt. The solvents used aseluents (ethyl acetate (technical grade), cyclohexane (technical grade))had been purified by distillation beforehand on a rotary evaporator.

For thin-film chromatography (TLC), ready-made PSC silica gel 60 F254plates from Merck KGaA, Darmstadt were used. The Rf values are reportedas a function of the eluent mixture used. The TLC plates were stainedusing a cerium/molybdatophosphoric acid solution as immersion reagent.Cerium/molybdatophosphoric acid reagent: 5.6 g of molybdatophosphoricacid, 2.2 g of cerium(IV) sulfate tetrahydrate and 13.3 g ofconcentrated sulfuric acid to 200 ml of water.

Gas Chromatography (GC/GCMS)

The gas chromatography studies (GC) on product mixtures and puresubstances were effected with the aid of the GC-2010 gas chromatographfrom Shimadzu, Japan. Analysis is effected on an HP-5 quartz capillarycolumn from Agilent Technologies, USA (length: 30 m; internal diameter:0.25 mm; film thickness of the covalently bound stationary phase: 0.25μm; carrier gas: hydrogen; injector temperature: 250° C.; detectortemperature: 310° C.; programme; “hard” method: start temperature of 50°C. for 1 min, heating rate: 15° C./min, end temperature of 290° C. for 8min). Gas chromatography-mass spectrometry analyses (GCMS) of productmixtures and pure substances were recorded with the aid of the GC-2010gas chromatograph combined with the GCMS-QP2010 mass detector fromShimadzu, Japan. Analysis is effected on an HP-1 quartz capillary columnfrom Agilent Technologies, USA (length: 30 m; internal diameter: 0.25mm; film thickness of the covalently bound stationary phase: 0.25 μm;carrier gas: hydrogen; injector temperature: 250° C.; detectortemperature: 310° C.; programme: “hard” method: start temperature of 50°C. for 1 min, heating rate: 15° C./min, end temperature of 290° C. for 8min; GCMS: ion source temperature: 200° C.).

Melting Points

Melting points were measured with the aid of the SG 2000 melting pointdetermination instrument from HW5, Mainz, and are uncorrected.

Elemental Analysis

The elemental analyses were conducted in the analytical division of theorganic chemistry department of Johannes Gutenberg University Mainz on aVario EL Cube from Foss-Heraeus, Hanau.

Mass Spectrometry

All electrospray ionization analyses (ESI+) were conducted on a QTofUltima 3 from Waters Micromasses, Milford, Mass. EI mass spectra and thehigh-resolution EI spectra were analyzed on an instrument of the MAT 95XL sector field instrument type from ThermoFinnigan, Bremen.

NMR Spectroscopy

The NMR spectroscopy studies were conducted on multi-nucleus resonancespectrometers of the AC 300 or AV II 400 type from Bruker, AnalytischeMesstechnik, Karlsruhe. The solvent used was CDCl3. The 1H and 13Cspectra were calibrated according to the residual content ofundeuterated solvent using the NMR Solvent Data Chart from CambridgeIsotopes Laboratories, USA. Some of the 1H and 13C signals were assignedwith the aid of H,H-COSY, H,H-NOESY, H,C-HSQC and H,C-HMBC spectra. Thechemical shifts are reported as δ values in ppm. For the multiplicitiesof the NMR signals, the following abbreviations were used: s (singlet),bs (broad singlet), d (doublet), t (triplet), q (quartet), m(multiplet), dd (doublet of doublets), dt (doublet of triplets), tq(triplet of quartets). All coupling constants J were reported in hertz(Hz) together with the number of bonds covered. The numbering given inthe assignment of signals corresponds to the numbering shown in theformula schemes, which need not correspond to IUPAC nomenclature.

General Procedure Specifications

All preparative procedures were conducted applying the Schlenk techniquewith argon as protective gas. Toluene and tetrahydrofuran were purifiedusing a Pure Solv MD-7 System and stored under argon before use.Triethylamine was distilled under argon from sodium ketyl before use.Phosphorus trichloride (Aldrich) was distilled under argon before use.All preparative procedures were effected in baked-out vessels. Therecording of nuclear resonance spectra was effected on Bruker Avance 300or Bruker Avance 400, gas chromatography analysis was effected onAgilent GC 7890A, elemental analysis was effected on Leco TruSpec CHNSand Varian ICP-OES 715, and ESI-TOF mass spectrometry was effected onThermo Electron Finnigan MAT 95-XP and Agilent 6890 N/5973 instruments,semi-automatic column chromatography was effected on a Teledyne IscoCombiflash Rf+.

Syntheses

a) (Anthracen-9-yloxy)dichlorophosphane (precursor)

Added dropwise to a stirred solution of PCl₃ (5.16 g; 37.6 mmol) in THF(25 ml) at 10° C. within 90 min is a mixture of anthrone (2.03 g; 10.44mmol) and triethylamine (2 ml) in THF (80 ml). After being left to standovernight, the mixture is filtered, the filtrate is concentrated todryness under reduced pressure and the residue obtained is taken up intoluene (50 ml). The mixture is filtered again, the solvent is removedunder reduced pressure and the yellow residue is dried at 50° C./0.1mbar. Subsequently, the solid obtained is stirred with hexane (30 ml) atroom temperature overnight. The mixture is filtered and the filtercakeis washed again with hexane (3×20 ml) and dried. Yield: 2.27 g (73%).³¹P-NMR (CD₂Cl₂): 202.5 (s) ppm.

b) 2-(Anthracen-9-yloxy)-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane(ligand 1)

To a mixture of pinacol (0.426 g; 3.606 mmol), triethylamine (4.6 ml)and toluene (14 ml), stirred at 0° C., is added dropwise a solution of(anthracen-9-yloxy)dichlorophosphane (1.117 g; 3.787 mmol) in toluene(17 ml). The mixture is allowed to come to room temperature, stirredovernight and filtered through a G4 frit coated with silica gel. Thefiltrate is concentrated to dryness under vacuum and the remainingresidue dried at 50° C./0.1 mbar for 5 h. Elemental analysis (calc. forC₂₀H₂₁O₃P=340.35 g/mol): C 70.35 (70.58); H 6.19 (6.22); P 8.97 (9.10)%,ESI-TOF/HRMS: m/e 341.13075 (M+H)⁺.

³¹P-NMR (CD₂Cl₂): 145.3 (s) ppm.

¹H-NMR (CD₂Cl₂): 1.27 (s, 6H); 1.55 (s, 6H); 7.32-7.43 (m, 4H); 7.85 (d,J_(HH)=8.6 Hz, 2H); 8.09 (s, 1H); 8.27 (d, J_(HH)=8.6 Hz, 2H) ppm.

¹³C-NMR (CD₂Cl₂): 24.9; 25.2; 86.5 (d, J_(CP)=7.5 Hz); 22.1; 123.0;124.9; 125.6; 125.7; 128.1; 132.2; 144.1 (d, J_(CP)=6.2 Hz) ppm.

c)4-(Anthracen-9-yloxy)-S-dinaphtho[2,1-d:1′,2′-f[]1,3,2]dioxaphosphepine(ligand 2)

To a suspension of anthrone (0.447 g; 2.30 mmol) in THF (5 ml), stirredat −20° C., is added dropwise a 0.32M solution of n-butyllithium inheptane (7.2 ml; 2.30 mmol). The mixture is allowed to come to roomtemperature and a solution of4-chloro-S-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine (0.807 g;2.30 mmol) in THF (6 ml) is then added dropwise with stirring. Themixture is stirred overnight and filtered. The volatile constituents ofthe filtrate are removed under reduced pressure, the resulting yellowsolid is taken up in toluene (10 ml), filtered through a G4 frit coatedwith silica gel and the filtrate is concentrated under reduced pressure.The resulting solid is dried at 50°C./0.1 mbar for 3 h. The work-up bycolumn chromatography (hexane/CH₂Cl₂, gradient hexane 100→0%; R_(f)=0.5for a 1:1 mixture of the mobile phases) gives 0.55 g (1.08 mmol; 47%) ofpure product. Elemental analysis (calc. for C₃₄H₂₁O₃P=508.511 g/mol): C80.80 (80.31); H 3.89 (4.16); P 6.02 (6.09) %. ESI-TOF/HRMS: m/e509.12979 (M+H)⁺.

³¹P-NMR (CD₂Cl₂): 149.7 (s) ppm.

¹H-NMR (CD₂Cl₂): 7.37-7.42 (m, 2H); 7.51-7.65 (m, 9H); 7.87 (d,J_(HH)=8.9 Hz, 1H); 8.02-8.14 (m, 6H); 8.40 (s, 1H); 8.57 (d, J_(HH)=8.9Hz, 2H) ppm.

¹³C-NMR (CD₂Cl₂): 122.1; 122.4; 123.0; 123.6; 123.8; 124.7; 125.0;125.7; 126.1; 126.5; 127.0; 127.3; 128.6; 128.9; 130.6; 131.1; 131.9;132.3; 132.6; 133.1; 133.4; 143.5 (d, J_(CP)=6.1 Hz); 147.4 (d,J_(CP)=2.7 Hz); 148.3 (d, J_(CP)=5.2 Hz) ppm.

d)2-([1,1′:3′,1″-Terphenyl]-2′-yloxy)-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane(ligand 3)

The required 2,6-diphenylphen-I-oxydichlorophosphine was prepared asdescribed in W. Maringgele, A. Meller, Phosphorus, Sulfur and Silicon1994, 90, 235-241.

To a solution of 2,6-diphenylphen-I-oxydichlorophosphine (1.048 g; 3.018mmol) in toluene (18 ml), stirred at 0° C., is added dropwise a mixtureof pinacol (0.3405 g; 2.881 mmol) and triethylamine (3.65 ml) in toluene(12 ml). The mixture is allowed to come to room temperature, stirredovernight and filtered. The filtrate is concentrated and the resultingresidue is crystallized multiple times from hot heptane. Yield: 0.295 g(0.752 mmol; 26%). Elemental analysis (calc. for C₂₄H₂₅O₃P=392.41g/mol): C 73.31 (73.45); H 6.42 (6.42); P 7.53 (7.89) %. ESI-TOF/HRMS:m/e 393.16143, (M+H)⁺.

³¹P-NMR (CD₂Cl₂): 142.9 (s) ppm.

¹H-NMR (CD₂Cl₂): 1.17 (s, 6H), 1.31 (s, 6H), 7.34-7.72 (m, 13H) ppm.

¹³C-NMR (CD₂Cl₂) δ 147.4 (d, J_(CP)=6.5 Hz); 139.4; 136.6; 130.9; 130.8;128.5; 127.6; 124.7; 85.3 (d, J_(CP)=8.0 Hz); 25.5; 24.8 ppm.

Hydroformylation

The hydroformylation reactions were conducted in a 200 ml autoclaveequipped with pressure-retaining valve, gas flow meter, sparging stirrerand pressure pipette from Premex Reactor AG, Lengau, Switzerland. Thetoluene used as solvent was purified using a Pure Solv MD-7 System andstored under argon.

For the experiments, solutions of the precursor complex (=catalystprecursor) and the ligand were mixed in the autoclave under an argonatmosphere. [(acac)Rh(COD)] (Umicore, acac=acetylacetonate anion;COD=1,5-cyclooctadiene) was used as precursor complex. For experimentsat a concentration of 100 ppm-m rhodium, 5 ml of a 4.32 millimolarsolution was placed in the autoclave. Subsequently, the mass of ligandcorresponding to a ratio L/Rh=5:1 was dissolved and mixed in 20 ml oftoluene. Into a pressure-resistant pipette was filled; 2.69 g (24.86mmol) of COD-1,5. The autoclave was brought to a pressure of 42 bar withsynthesis gas (Linde; H2 (quality 5.0: CO (quality 4.7)=1:1) and heatedto 60° C. After reaching the reaction temperature, the diolefin wascompressed into the autoclave. The reaction was conducted at a constantpressure of 50 bar (closed-loop pressure controller from Bronkhorst, theNetherlands). After the reaction time had elapsed, the autoclave wascooled to room temperature, decompressed while stirring and purged withargon. 1 ml of each reaction mixture was removed immediately after thestirrer had been switched off, diluted with 5 ml of pentane and analyzedby gas chromatography: HP 5890 Series II plus, PONA, 50 m×0.2 mm×0.5 μm.

The results of the hydroformylation experiments are compiled in thefollowing table. The conversion specified includes in this case bothmonoaldehydes and dialdehydes.

Standard experimental conditions: [Rh]=0.717×10⁻⁴ M,Rh/ligand/COD-1,5=1:5:1151, solvent toluene.

TABLE 1 Conversion Ligand p [bar] T [° C.] t [h] COD-1,5 [%]  1* 50 60 491 2 50 60 4 54 3 50 60 4 76 *method according to the invention

As the experimental results show, the object is achieved by theinventive method.

1. Method for hydroformylating cyclooctadiene, comprising the methodsteps of: a) initially charging cyclooctadiene; b) adding a complexcomprising: a metal atom selected from: Rh, Ru, Co, Ir, and a ligandhaving the structure (1):

or adding a precursor complex comprising a metal atom selected from: Rh,Ru, Co, Ir, and a compound having the structure (1):

c) feeding in H₂ and CO, d) heating the reaction mixture, wherein thecyclooctadiene is converted to an aldehyde.
 2. Method according to claim1, wherein the metal atom is Rh.
 3. Method according to claim 1, whereinthe precursor complex comprises cyclooctadiene.
 4. Method according toclaim 1, wherein the precursor complex is [(acac)Rh(COD)].
 5. Methodaccording to claim 1, wherein the reaction mixture is heated to atemperature in the range of 50° C. to 70° C. in method step d).